1. Field of the Invention
The invention relates to a method and apparatus for forming a liquid impervious floor under a chemical dump site form a string of interlocking floor elements.
2. Description of the Prior Art
The problem of aging and leaking chemical dump sites is one that is slowly being recognized as a major health hazard. The most common method of dealing with the problem is to cover the site over with a sealing material and then build a wall around the area. Unfortunately that approach is expensive. Alternatively the entire site can be dug up and removed to an unpopulated area where a new dumping pit has been dug. The new pit can have a preformed floor and preformed sidewalls. That approach is also very expensive and time consuming. What is required is a relatively inexpensive and easy way to build containment barriers in situ around and existing dump site.
One of the more relevant prior art patent references teaches a method for building an underground barrier. Japanese Pat. No. 55-9571 entitled "Forming Process for Underground Hardened Matter" discloses a technique for building a horizontal subterranean wall. Initially, a boring device is placed in a trench. A horizontal hole is then bored in the earth. A casing is subsequently placed in the bored hole and a reinforcing means is placed into the casing. Ground hardening material is then pumped into the casing and the casing is then pulled back, allowing the ejected material and the ground to harden. The sequence is repeated at an adjacent position to produce a continuous wall. The Japanese patent differs in several important respects from the present invention. In particular, there is no use of interlocking adjacent channels which stay in place after the ground hardening material is forced into the bore hole.
U.S. Pat. No. 2,882,714 is of general interest in that is discloses the use of interlocking blocks to line the floor of a structure requiring an impervious liner. The patent discusses the use of tenons and recesses which interlock with each other in a dovetail fashion.
U.S. Pat. No. 1,662,727 discloses an invention entitled "Metallic Bonding for Concrete Supports". I-beams are notched and laid on top of each other in order to form a crib which can be filled with a suitable concrete material. The reference is useful only in that it discloses the use of interlocking structural members which receive a grout-like material.
U.S. Pat. No. 4,104,837 is interesting in that it discloses a rather unusual technique for constructing a wall. Modular wall units interlock along their side edges and can be filled with insulation or other appropriate material. The units are open along their sides thereby permitting the flow of insulation between adjacent modular sections. The teaching in U.S. Pat. No. 4,104,837 appears to differ from the present invention in that it does not allow itself to be driven into position to form the floor of a chemical waste site. In addition, that patent does not appear to disclose a means of communication between the wall units and the exteriors thereof (as opposed to between interior sections of adjacent wall units).
U.S. Pat. No. 4,358,221 is directed towards the containment of chemical waste. The reference refers to a "tongue and groove" section that appears to relate only to the method by which the over burden is attached to the lower portion of the structure.
U.S. Pat. No. 4,252,462 discloses a structure for the treatment of surface chemicals for landfill sites. The structure includes a liquid impervious bed of suitable thickness
U.S. Pat. No. 3,113,628 is of interest in that it discloses a machine for drilling a horizontal bore into the ground and then placing a desired length of pipe into the bored hole. It is believed that there are other devices which will perform the same function.
U.S. Pat. No. 4,365,913 describes a method of installing pipe horizontally in the ground from a vertical access shaft. This patent appears to describe yet another technique for laying a section of pipe or other material horizontally.
U.S. Pat. No. 4,369,002 discloses a method of emptying pipe that has been driven into the ground. It is likely that there are other methods for performing the same function.
Finally, U.S. Pat. No. 4,146,347 is of interest in that it discloses yet another technique for boring horizontal holes. The pipe is vibrated into position before the dirt is pulled out.
While the prior art references are relevant to the general concept described in this application, none of them, either taken in combination or individually appear to hint, teach or suggest the novel invention described herein for forming a liquid impervious floor under a chemical dump site or the like.